Electrical measuring instrument.



M. J. WOHL & H. HERTZBERG. ELECTRICAL MEASURING INSTRUMENT.

APPLICATION FILED MALSI, 1908. 947,267. Patented Jan. 25, 1910.

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V I UNITED STATES PATENT OFFICE.

HLUBIOEJ. 'WOHL, NEW YORK, AND HARRY HER-TZBEBG, OF BROOKLYN, NEW YORK, ASSIGNOBS TO ABBOT A. LOW, OF HOBSESHOE, NEW YORK, MAURICE J. WOHII, OF NEW YORK, N. Y., AND HARRY HEBTZBEBG, OF BROOKLYN, NEW YORK,

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947,267. p fi a 01 Letter! Patent Patented Jan. 25, 1910.

Application filed larch 31, 1908. Serial No. 424,825.

To all whom it concern: wire at 3. Extending from are the Be it known that we, MAURICE J. Worn.

auxiliary leads 4, 5 and 6 which supply the 65 and HABBY Hnn'rznnno citizens of the current to lam s or other current consuming United States, and residents, respectively, of the city of New York, borough of Manhattan, county and State of New York, and of the city of New York, borough of Brook- 1 county of Kings, and State of New ork, have invented certain new and useful Improvements in Electrical Measuring Instruments, of which the following is a specification.

This invention relates to electrical measuring instruments and more articularly to an instrument adapted to indicate the maximum electrical energy flowing in any multicircuit The iect sought to be obtained is to rovide 'a simple device of this character w ich may be embodied in a single instrument adapted to be used with a multi-circuit system, with especial reference to the ordinary three-wire system of distributing now in use.

In devices of this nature it is desirous to obtain a record of the maximum current which flows in a circuit for an appreciable time. This has been found to be a comparatively simple matter in an ordinary twowire circuit, but in three-wire or other multicircuit systems it has been diflicult to obtain directly a correct record of the maximum current. Among the methods which have been used is that of us' two se arate instruments, but this metho it willbe readil understood, does not give a correct resu t as the two sides of the circuit are seldom balanced, that is, using the same amount of current, and consequentl the maximum current consumption is so om correctly indicated by the combined readings of the two instruments.

In some of its features the device herein shown and described is similar to that shown in our copendiriglarpplication filed Mch. 20, 1908 un er Ser. 0. 422,275. The distinguishin features will be more fully described ereinafter.

In the drawing is shown, a semidiagrammatic view of an instrument embodylnfilolur invention used in connection with an or ary three-wire system.

The two outside wires or mains of the 'systemareshownatland2andtheneutral a paratus, which is indicated diagrammatica in the drawing.

the instrument shown in the drawing 7 and 8 are two thermall expansible wires which are supported at eir outer ends by means of ielding spring supports 9 and 10, res ective y. At their inner ends the wires 7 an 8 are connected to arotatable'member 11 to which is also attached an arm 12 which carries an adjustable weight 13 which tends to preserve the wires 7 and 8 under tension.

The arm 14 is also attached to the rotatable member 11 and so positioned as to engage an indicator 15 which is pivotally mounted referably provide with an inclined surace on one side and a radial surface on the other side permitting the indicator 15 and its engaging member 17 to be moved over the 30 same in one direction only. A suitable handle 19 may be provided on the indicator 15 by means of which the same is raised so that the engaging member 17 is out-of engage= ment with the serrationsand the indicator may be swung back to its initial position.

Surrounding the thermally expansible members 7 and 8 are two separate heating coils insulated from each other and the wires 7 and 8. These coils are connected in series respectively with the leads 4 and 5 of the suppl circuit and when the current flows in elt er one or both of these leads the heatin coils cause the thermally expansible \vlres 7 and 8 to expand, allowing the weight 13 to rotate the member 11, which in turn causes the arm 14 to engage the indicator 15 and swing the same about its pivot over the index plate. When the current is reduced or cut out entirely the wires '7 and 8 resume their normal temperature and in cooling and contracting rotate the member 11 and its attached parts to their original position.

It is not necessary 'to describe herein the operation of a three .wire system and it will be seen that if the current consumption at rovided with an' 75 a spring supports 9 and 10 and is supported by a heating coil connected in series with the auxiliary lead 6 from the neutral wire. The resistance of this last named heating coil is one-half of that of either of the coils surrounding the wires 7 and 8 and, consequently, the heating effect is one-half for the same amount of current.

The action of the heatinglcoil in the neutral circuit 6 is to cause t e compensating wire 19 to expand, allowing the sprin supports 9 and 10 to take up a part of t e expansion of the wires 7 and 8 thus partly neutralizing the combined effect of theheating coils inpseries with the leads 4 and 5. The combined efl'ect of these heating coils with the construction described will be" found to be constant re ardless of whether the current consuming evices are the same on either side of the circuit or not and thls result may be expressed by the formula X +Y (Z +2); in which X is the current on one outside line; Y is the current on the other outside line and Z is the current in the neutral line, the element of resistance bein omitted as it is common to each. From this it will be seen that the total expansion will vary as (X+Y) The compensating wire 19' has an additional ,function in providing for changes of tem erature in the surrounding air which won d ordinarily cause the wires 7 and 8 to expand or contract and so move the indicator. By making this compensating wire 19 so that it will have the same ex ansion or contraction for a given chan o temperae ture as wires 7 and 8, it wil be seen that a under these conditions the spring supports 9 50 and 10 will be moved and an rotative movement of the member 11 w' l be prevented. It will thus be seen that with a suitable marking of the index plate the indicator will show directly the desired result regardless of the conditions under which the current is used in the threewire system.

As manychanges could be made in the above construction and many apparently widely different embodiments. ofour inven tion designed without departing from the scope thereof, we intend that all matter contained in the above description shall be interpreted as illustrative merely of an operative embodiment of our inventionand not in. a Iimitingsense.

\Vhat we claim is:

1. In an electrical measurin instrument for three wire circuit, the combination of an indicator pivotally mounted to permit a swinging movement and a lon 'tudina-l movement thereof, a serrated mem er over which said indicator travels the serrations of said member being formed to permit said indicator to travel thereover in one direction but to hold the same a ainst a return movement, an operating mem er operatively enga 'ng said indicator for movement in one irection only, means for moving said operating member in this direction, a thermally expansible wire operatively connected to said operating member, means for heating said wire by the cumnt flowing in the outside lines of said three wire circuit, a cooperating thermally ex ansible wire, and means for heating said last named wire by the current flowing in theneutral line of said circuit.

2. In an electrical measuring instrument for three wire circuits, the combination of an indicator, an operating member operatively engaging said. indicator for movement in one direction only, means for moving said operating member in this direction, a thermally expansible wire operatively connected to said operating member, means for heating said wire by the current flowing in the outside lines of said three wire .CllClllt, a 00- operating thermally ex ansible wire, and means for heating said ast named wire by the current flowing in the neutral line of said circuit.

3. In an electrical measuring instrument for three wire circuits, the combination of an indicator, an operating member operatively engaging said indicator for movement in one direction only, means for moving said operating member in this direction, a pair of yielding supports, a pair of thermal members each extending from one of said supports to said operating member means for eating said thermal members by the current flowing in the outside lines of saidcircuit, a compensatin thermal member extending between sai yieldingsupports, and

means 'for heating said compensating member by the current flowing in the neutral lines of said circuit.

4. In an electrical measming instrument adapted for use with a three wire circuit, thelcombinationof a movable indicator, an operating member ada ted to have operative connection with said indicator when moved in one direction only, means operative to move said member in this direction, a wire under tension heated and expanded b current passing through said circuit, sai wire" havi f connection with said operating member w ereby the expansion of the wire al- Iov/ said means to move saith-member, means for heating said wire from the current in said circuit, and a compensating wire opto move said member, means for heating erated by the current in the neutral line or said wires by the current to be measured, a said three-wire circuit. compensating wire-stretched between saidv In an electrical measuring instrument spring supports, and means for operating 5 adapted for use with a three wire circuit, said compensating wire by the current in the 20 the combination of a movable indicator, a neutral line of saidthree-wire circuit. pivoted operating member adapted to have Signed at New York, in the county of operative connection with said indicator Kings and State of New York, this 27th when moved in one direction only, means day of March, 1908.

10 operative to move said member Hi this direction, opposed spring supports, thermal wires stretched between said supports and said pivoted member at points on opposite Witnesses: sides of the pivotal axis thereof, whereby JOHN H. FLATHMANN,

15 the expansion of the wires allows said means GEO. TELLING Gmnmcs. 

